With the development of the mobile communication technology, smart terminals such as mobile phones and tablet computers have become popular.
For example, most mobile phones can be used to send short messages and make calls. When its user encounters an emergency such as being threatened, the user may call to a contact, e.g., the police or a relative, for help. In the related art, when the user makes the call, the user searches a contact list for a phone number of the contact manually, or inputs the mobile phone number of the target contact into the mobile phone manually and uses a predetermined gesture start the call. When the mobile phone receives the call instruction, it tries to connect the contact, so that the user can seek for help.